Demonoid is a BitTorrent tracker website. It was apparently set up by an anonymous Yugoslav known only as Deimos. The website indexes torrents uploaded by its members. These torrents can then be searched and the content shared using the peer to peer BitTorrent protocol.
Demonoid is one of the largest BitTorrent trackers and its torrents are found on other BitTorrent search engines.
Demonoid has been down and the constant rumor is that Demonoid is out of business.
http://bu.bulicio.us/gadgets/demonoid-taken-down/
http://www.demonoid.com/